1. Field of the invention
The invention relates generally to an improvement in the field of welding of metals reactive in the atmosphere during welding and more particularly, but not by way of limitation, to an open faced trailing weld shield for a welding torch that provides for viewing of the weld puddle and the solidifying weld while shielding such weld areas so that the weld procedure may be monitored as it is proceeding.
2. Prior Art
In the welding together of certain metals such as aluminum-lithium, titanium, certain steels, nickel and cobalt alloys a problem is encountered. As the welding process, such as plasma arc welding, gas tungsten arc welding, or gas metal arc welding, is conducted the weld puddle and the solidifying weld area must be suitably protected by an inert gas such as argon or helium since such metals, in the absence of a protective atmosphere, at an elevated temperature react with the oxygen in the atmosphere to form undesirable oxides.
The commonly used expedient in the prior art to overcome this problem is described at page 81 of the American Welding Society's Welding Handbook, Vol. 2, 8th Edition. In the absence of a controlled atmosphere welding chamber that has been purged of contaminants and replaced by a suitable shielding gas, the common expedient that is available for practical application in a production environment is a trailing shield. This trailing shield commonly includes a metal chamber having an open end that is configured to fit the surfaces to be welded or to suit the individual welder. A gas tungsten arc welding torch extends through the top of the shield for performing the welding procedure. A suitable inert gas is also introduced into the shield chamber to provide a protective inert gas shield for the solidifying weld as it cools to a temperature at which it is no longer reactive with the normal atmosphere. The shield chamber also preferably is packed with a suitable stainless steel wool or copper wool to provide a more even flow of inert gas to the work piece.
Unfortunately, the conventional trailing shield as described above suffers from a serious shortcoming. The weld operator in using the conventional shield, since the shield is closed to viewing, must wait until the weld emerges from the trailing edge of the shield and becomes visible to the operator or to a monitoring vision system. If there is a problem with the weld it is too late to change the welding parameters to correct the welding procedure. Obviously, such a welding procedure leaves something to be desired since the cost of scrap or rework of welded members of a very expensive metal is significant.
Accordingly, it is a general object of the present invention to provide a trailing shield for the welding of metals that are reactive with the atmosphere at an elevated temperature which provides viewing of the weld as it proceeds while yet providing a protective inert gas protective shield.
It is a further general object of the invention to provide a trailing shield that may be easily and separably attached to a welding torch which permits viewing of the welding operation in real time and immediate correction of any welding parameters that are not optimum.
It is a specific object of this invention to provide a practical, easily fabricated trailing weld shield that may be easily constructed for use with processes for welding reactive metals and that permits viewing of the weld puddle and solidifying weld area while the welding operation is being conducted in an inert gas shielding atmosphere.
The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or by modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.